The following documents are believed to reflect the state of the art:
Amkor Technologies 3D—Through Silicon Via (TSV) Wafer Finishing and Flip Chip Stacking Solutions is described in a document available on the World Wide Web at www.amkor.com/go/TSV.
Hardware Trust Implications of 3-D Integration, WESS'10 (Workshop on Embedded Systems Security), Huffmire, et al., Oct. 24, 2010.
Improving the Quality of a Physical Unclonable Function Using Configurable Ring Oscillators, A. Maiti and P. Schaumont, International Conference on Field Programmable Logic and Applications, 2009. FPL 2009.
Physical Unclonable Functions for Device Authentication and Secret Key Generation, E. Suh and S. Devadas, DAC 2007, Jun. 4-8, 2007.
U.S. 2007083767, Apparatus and Method for Detecting Falsification of External Data, of Kumamoto, describes an external data falsification detecting system including a data acquirer section configured to acquire an external data at a time of system start and during system operation. A normal hash value of the external data is previously stored in a storage unit. A comparator section calculates a hash value of the acquired external data, compares the normal hash value and the calculated hash value, and determines that the external data was falsified such that a predetermined operation limitation is carried out, when the normal hash value and the calculated hash value are not coincident with each other.
WO2011086051, Integrated Silicon Circuit Comprising A Physically Non-Reproducible Function, And Method And System For Testing Such A Circuit, of Inst. Telecom Paris Tech., describes an integrated silicon circuit that comprises a physically non-reproducible LPUF function enabling the generation of a signature specific to said circuit. Said function comprises a ring oscillator consisting of a loop through which a signal flows, said loop consisting of N topologically identical delay channels, connected to each other in series and an inversion gate, wherein a delay channel consists of M lag elements connected to each other in series. The function also comprises a control module that generates N control words (C1, C2), said words being used for configuring the value of the lag inserted by the delay channels on the signal flowing therethrough. A measuring module measures the signal frequency at the output of the last delay channel after updating the control words, and means for deriving the measurements of the frequencies of the bits forming the circuit signature.
EP 2320344, Key Generation, of the Massachusetts Institute of Technology, describes a chip and a method is provided for operating a chip to generate and use a secret key to decrypt contents of a memory, wherein the method comprises: receiving at a PUF circuit in the chip a challenge stored on the chip; outputting from the PUF circuit a k-bit response; combining in the chip the k-bit response with the content of fuses to produce a key; and receiving the key at a decrypter and decrypting contents of a memory in the chip.